Geneticially Modified Bt Corn
Why Bt corn? Bacillus thuringiensis' '''is a soil bacterium that can be found in many locations around the word. This bacterium has the ability to produce crystal proteins (Cry proteins), which selectivity destroy specific groups of insects. The Cry proteins are stomach poisons, which must be ingested to kill a certain insect. Once eaten, the insect's digestive enzymes convert the protein into its toxic form, resulting in intestinal cell rupture and death. Bt corn is genetically modified to contain the Cry proteins. Although insecticides are often used, their action has proved to be inconsistent or ineffective within the agricultural industry. Bt insecticides have shown to be sensitive to UV radiation and heat, as well as applied with incomplete coverage, and reduced toxicity to older larvae. By genetically modifying corn to produce its own Bt proteins, these short falls can be resolved. Since the Bt protein is present consistently within the plant tissue, it is there when and where larvae feed. This eliminates the need to apply pesticides at the right time, as well as the equipment and labor required for application. Overall, genetically modified Bt corn is an effective and efficient system to expose Bt proteins to target pests. Generation of Bt corn In order to generate Bt corn, the Cry protein gene must be extracted from the DNA of ''Bacillus thuringiensis. ''This is done using various restriction enzymes in either plasmid or chromosomal DNA. The gene of interested is then amplified using polymerase chain reactions, where the DNA is inserted into a plasmid to be replicated. Containing an antibiotic resistance gene, the plasmid allows for PCR through the process of transformation. The promoter CaMV35s is added to the gene to control when and where in the plant the gene will be expressed. This specific promoter comes from the cauliflower mosaic virus, and causes the gene to be expressed in tissuee sequence is replaced with the bacterium's A-T nucleotide. Gene markers and a termination sequence is also added to the isolated gene. This aids in ensuring replication is stopped once the gene of interested is copied, and also helps to identify the plant cells which have specific integration of the transgene. At this point, the physical DNA containing the Cry protein can be inserted into the plant cells. Currently, DNA from one of the three Cry proteins (Cry1Ab, Cry1Ac or Cry9C) are used in this process. Introduction of new DNA can be done through the gene gun method, or the micro-projectile bombardment method. A stainless steel gun is connected to a vacuum pump, and helium is released within the gun's chamber at a higher pressure, which disrupts the activity of a metal disk. The energy is then transferred to a dish containing tungsten particles 1 micron in diameter. These particles are infused with and contain the DNA molecules, which travel 1300 feet per second to penetrate the plant cells and therefore released the DNA within the nucleus. Once the Cry protein DNA comes incorporated into the plant's chromosomes, plant breeding takes place. A tissue sample is obtained and grown in medium that contains a series of hormones and nutrients allowing susceptibility testing to be done to confirm the transformation. If confirmed, the seeds of the transformed plant will also contain the inserted DNA, and these seeds are then sold and used throughout the agricultural industry. Economic Effects The advantages of growing Bt corn are seen two fold from an economic standpoint. Since its introduction into agriculture, Bt corn has yielded $537 million, which is an increased of about $1.31 per acre planted. There has been an introduction of a "technology price," which is an increased price in corn seeds as a result of the genetic modifications. This is still worth the viability of corn however, as the prices of pesticide application and loss of the crop due to infestation costs farmers millions. Altogether, this form of genetic modification is a safe and sufficient way to grow and maintain corn as a crop for both farmers, and the dependent population. Resources [http://whatisbtcorn.pbworks.com/w/page/12449526/Biochemical%20Explaination%20of%20Bt%20Corn 1. "Biochemical Explaination of Bt Corn." ''What Is Bt Corn? /. PB Works, n.d. Web. 05 Oct. 2014.2. ] [[wikipedia:Genetically_modified_maize|2. "Genetically Modified Maize." Wikipedia. Wikimedia Foundation, 19 Sept. 2014. Web. 04 Oct. 2014.]] [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3473024/ 3. Buzoianu, Stefan G., Maria C. Walsh, Mary C. Rea, Orla O'Donovan, Eva Gelencsér, Gabriella Ujhelyi, Erika Szabó, Andras Nagy, R. Paul Ross, Gillian E. Gardiner, and Peadar G. Lawlor. "Effects of Feeding Bt Maize to Sows during Gestation and Lactation on Maternal and Offspring Immunity and Fate of Transgenic Material." National Center for Biotechnology Information. U.S. National Library of Medicine, 16 Oct. 2012. Web. 05 Oct. 2014.] [http://www.extension.umn.edu/agriculture/corn/pest-management/bt-corn-and-european-corn-borer/ 4. "Bt Corn and European Corn Borer." : Pest Management : Corn Production : University of Minnesota Extension. University of Minnesota, n.d. Web. 02 Oct. 2014.]